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背衬对压电传感器瞬态特性影响的模拟研究 总被引:1,自引:1,他引:0
接收信号在换能器压电层中的多次反射及波形转换对超声检测的灵敏度和分辨率有重要影响,提高其接收性能的关键是优化换能器背衬结构与材料参数.该文采用Ansys软件中力-电耦合瞬态模拟法,分析了背衬结构的几何参数、材料参数对压电直探头瞬态接收性能的影响,得到了压电换能器中不同时刻的弹性波场、电场分布及输出电压响应曲线,拟合了换能器灵敏度、分辨率与背衬结构几何、材料参数间的关系.研究结果表明,合理选择背衬结构与材料参数对消减接收信号的多次反射,提高换能器接收性能有明显的作用.运用有限元软件分析背衬结构对压电探头瞬态接收特性的影响,是优化背衬结构与材料参数重要方法之一. 相似文献
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用声发射监测镀镍钢带拉伸断裂过程,对PCI-2声发射系统采集到的声发射信号进行参数分析,结合拉伸机的测试结果,研究声发射信号的特征参数与试件拉伸力学行为间的相关性。研究结果表明,拉伸断裂过程中试样声发射信号的振铃计数、能量、持续时间、幅值等声发射特征参数能表征试样损伤过程,损伤随应变的变化规律;试样变形至屈服阶段、颈缩断裂阶段时,声发射信号的能量和振铃计数都会增加;试样开始颈缩时所发出的声发射信号的幅值主要分布在43~79dB;声发射技术是一种监测镀镍钢带失效行之有效的方法。。 相似文献
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The deformation texture and surface microstructure of nickel coating induced by deep cup-drawing were studied by X-ray diffractometry and SEM. The steel sheet with nickel coating was firstly punched to designed degree of cup shapes. Then the texture of the coating was determined by XRD and the surface microstructure was observed by SEM. The results indicate that, the nickel coating material includes three kinds of textures, i.e. Ni (111), Ni (200) and Ni (220). After cup-&awing deformation, there doesn't appear new texture component for nickel coatings but the change of the intensity of the deformation textures. In the cup-deformation process, the two kinds of main textures Ni (111) and Ni (200) increase in the first and second cup-drawing procedures and then reduce quickly in the third and fourth drawing procedure. However, for the Ni (220) texture, it always increases in whole cup-drawing procedures. With the increase in the drawing, there are some cracks to be found, but not delamination. This shows that nickel coating and the substrate have a good combinable performance. 相似文献
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本文应用声波透射、散射和反射理论,提出了预应力孔道灌浆密实度检测的方法。首先用声波透射法在预应力孔道两端快速确定钢绞线的固结波速,再根据相关性找出灌浆等级较差的预应力孔道,然后在灌浆不密实的预应力孔道侧面用声波散射扫描式方法确定灌浆不密实区域的位置。 相似文献
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The deformation-induced textures in electrodeposited nickel coating were numerically studied. The finite element method (FEM) for polycrystalline was developed based on Taylor model. Then the deformation-induced textures in electrodeposited nickel coating with initial random and lamellar texture were simulated under tensile load. It is found that the initial textures significantly influence the deformation-induced textures. For nickel coating with the initial random textures, when (he tensile strain is about 40%, there are some lamellar textures. For nickel coating with the initial lamellar textures, the lamellar texture is more intensity with the increase of the tensile strain. With the increase of the tensile strain in the coating, there are more pronounced element distortion and a more inhomogeneous deformation. Due to the different crystal orientations, the grain-scale roughness is observed. With increasing tensile strain in the coating, the surface grain-scale roughness increases on the flee surface. The surface roughness of the coating with initial random texture is lower than that with the initial lamellar texture. 相似文献
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为研究全螺纹高强锚栓的黏结锚固性能,以高强锚栓类型、高强锚栓直径d、锚固长度la及混凝土保护层厚度c为试验参数,进行了24组共计48个高强锚栓的拉拔试验。结果表明:端头高强锚栓较直高强锚栓可有效减小其所需的锚固长度。直高强锚栓黏结力主要集中在la=10d以内;增加c可以提高其锚固性能,增加la可以减小c对其黏结锚固性能的影响。混凝土的破坏程度和la直接影响高强锚栓受拉过程中能量转化和消耗。中国规范中有关锚栓锚固长度的设计方法过于保守。 相似文献